The invention relates to the use of one or more spring assemblies, for example leaf springs with rollers, which engage notches in the tape cartridge, when the cartridge is fully inserted into the cartridge shuttle of an automatic loader mechanism. The spring(s) and the associated housing are designed to de-rate the spring force and thereby minimize the force on the cartridge during insertion and removal and to reduce friction and scraping of the cartridge during such operations.
Computers utilize a variety of magnetic media devices for the storage of software programs and data. Information recorded on the magnetic medium takes the form of flux transitions that represent the binary xe2x80x9c1""sxe2x80x9d and xe2x80x9c0""sxe2x80x9d that form the digital information. Tape cartridges, such as single-reel tape cartridges, are commonly used in library or other archival data storage applications. In such applications, a user or a robotic mechanism selects a tape cartridge for processing and inserts the cartridge into a tape drive coupled to a computer. In a fully automated system, a mechanism within the tape drive loads the tape from its entry point to a position in which the tape becomes accessible for read-from and write-to operations.
A variety of different size data tape cartridges are available. The drives for the different size cartridges, however, must be substantially the same size, so as to fit within a standard size slot or space available within the framework of a personal computer or the like. Larger cartridges enable storage of more data on the tape within, however, the larger the cartridge the more difficult it is to design a drive mechanism to fit within the design envelope.
For example, some single reel cartridges are 105.4 mm wide, by 102 mm long by 21.5 mm high. Such a cartridge, by itself fills a substantial portion of the design envelope for the tape drive. As a result, tape drives for this type of cartridge have utilized manual loading mechanisms. All movement and operations to load the tape cartridge into the drive, open the tape door for access to the tape leader and engage the tape drive gear to the drive motor gear have been manual in nature. A portion of the cartridge remains outside the drive, even in the fully loaded position.
Hence, a general need exists for an automatic loading mechanism for data tape cartridges that takes up the minimum amount of space within the design envelope of the tape drive, to allow the mechanism and the drive to handle as large a cartridge as possible. Also, a need exists for a loader mechanism of this type that is particularly durable and can operate successfully for a large number of loading/unloading cycles without any jams or other failures.
Applicants and/or coworkers at the assignee of the present case have developed a fully automated tape cartridge loader system specifically designed for high durability in extended usage yet configured so that the elements thereof occupy minimal space and thereby meet the above-stated general need.
This tape cartridge loader includes a moveable shuttle, for receiving the tape cartridge and moving to and from a position within the system in which the cartridge is operatively loaded into the tape drive. The shuttle motion is bidirectional, typically front-to-back and top-down during loading. The loader also includes a conveyor, which is mounted for linear motion. The conveyor, however, supports the shuttle in such a manner that linear motion of the convey produces the desired two-dimensional motion of the shuttle and the cartridge.
For example, the conveyor has two sidewalls and one or more cam profiles in each sidewall. Corresponding cam follower bearings are attached to the sides of the shuttle for engagement with the respective cam profiles. The loader includes a substantially flat, rotatable actuator arm. The arm includes a groove, the edges of which serve as cam profiles. These later profiles drive a bearing attached to the conveyor, to move the conveyor along a linear path during loading and unloading operations. As the arm induces the linear movement of the conveyor, the conveyor interacts through the follower bearings and the cam profiles on its sides, to produce the necessary bidirectional movements of the shuttle during loading and unloading operations.
The initial design of this loader mechanism is disclosed for example in copending U.S. application Ser. No. 09/314,970 filed May 20, 1999 entitled xe2x80x9cTAPE CARTRIDGE-LOADING MECHANISMxe2x80x9d (50103-224) and in copending U.S. application Ser. No. 09/314,974 filed May 20, 1999 entitled xe2x80x9cTECHNIQUES FOR COMPENSATING FOR HIGH INITIAL UNLOADING FORCE REQUIREMENT IN TAPE CARTRIDGE-LOADING MECHANISMxe2x80x9d (50103-223), the disclosures of which are entirely incorporated herein by reference.
Of note for purposes of discussion here, the initial version of the loader system included springs on the shuttle for registration with notches in the lower side edges of the tape cartridge. Specifically, near the lower front corner, each sidewall of the shuttle included a rectangular opening, which extended somewhat into the bottom plate. A flat leaf spring was riveted to each shuttle sidewall so that a distal end thereof extended through one of the openings into the interior of the cartridge shuttle assembly. When a cartridge was fully inserted into the shuttle, the springs engaged the notches in the tape cartridge to secure the cartridge within the shuttle during the loading and unloading movements of the shuttle.
The insertion and removal forces on the cartridge, particularly for certain tape library applications, need to be fairly low. The registration spring design discussed above created excessive forces resisting insertion and removal of the cartridge, for example requiring too much force for some types of robotic arm intended to select and move cartridges to and from the loader itself. Additionally, friction of the springs with the sides of the cartridge caused extreme wear on the cartridge. Furthermore, the attendant scraping created debris, which could potentially contaminate the tape path.
Hence there is an additional need for a registration mechanism for a tape cartridge loader, wherein the forces caused by the registration mechanism are minimal during cartridge insertion into and removal from the loader, and that reduces or eliminates the debris otherwise generated by scraping of the cartridge by the springs. The registration mechanism, however, must still provide ample registration force to secure the cartridge within the shuttle during the loading and unloading movements of the shuttle.
The inventive concepts alleviate the above noted problems with registration systems of tape cartridge loader mechanisms and thereby meet the stated needs. For example, the invention involves de-rating the force applied by one or more registration springs prior to and/or during insertion of a tape cartridge into the loader. However, when the cartridge is fully inserted in the loader and then moved away from the initial loading position, the de-rating stops, and the spring(s) apply the full force to the registration notch(es), to insure stable transport of the cartridge to and from actual engagement with the associated tape drive. An aspect of the preferred embodiment involves reducing friction and scraping force on the cartridge by utilizing a roller near the end of the registration spring to actually contact the surface of the cartridge.
Hence one aspect of the invention relates to an automatic tape cartridge loader. The loader includes a mechanism for receiving the tape cartridge and automatically moving the cartridge between an initial position and an operative position. The initial position, for example, enables insertion and extraction of a cartridge from the loader. In the operative position, the cartridge is in engagement with a data tape drive serviced by the automatic tape cartridge loader. The loader also includes means for latching the tape cartridge within the loader mechanism with a de-rated registration force at the initial position and with a full registration force as the loader mechanism moves the cartridge to or from the operative position.
The preferred embodiment utilizes two leaf springs, one mounted on each side of the cartridge shuttle to engage a respective side of the cartridge. The de-rating of the springs is achieved by causing an extension at the distal end of each spring to engage a ramp, formed on the support of the loader housing, as the shuttle returns to its initial position for loading and unloading of the cartridge. The engagement with the ramp deflects the spring outward away from the cartridge, an amount sufficient to reduce the inward force that the spring applies to the cartridge. However, the retraction is not so complete as to avoid contact or eliminate the spring force on the cartridge completely. In this way, the force necessary to insert the cartridge is reduced, the springs still create a force and some minimal resistance to cartridge insertion.
Movement of the shuttle away from the initial position causes the extension to slip off of the ramp. The spring then applies its full force to the registration notch of the cartridge. In the preferred embodiment a roller bearing mounted on the spring serves as the actual registration device for contacting the side of the cartridge and engaging the notch.
Another aspect of the invention relates to a tape cartridge latching mechanism, for an automatic tape cartridge loader. The latching mechanism comprises a spring attached to the cartridge shuttle and a registration device coupled to the spring for engaging a registration notch on the tape cartridge with a force applied by the spring. The loader includes a fixed feature adapted to engage a portion of the spring when the cartridge shuttle is in the initial position. This engagement retracts the spring and thereby de-rates the force applied by the spring during insertion and removal of the tape cartridge. The location of the feature is such that the feature does not engage the spring, when the cartridge shuttle is moved away from the initial position.
In the preferred embodiment, the loader includes a frame housing and a conveyor mounted for linear motion within the frame housing. A cam and follower arrangement mounts the cartridge shuttle within the conveyor, in such a manner that the linear movement of the conveyor causes a bi-directional movement of the cartridge shuttle within the frame housing. A drive motor rotates an actuator arm to cause the linear movement of the conveyor, which causes the bi-directional movement of the cartridge shuttle. The movement of the shuttle transports the cartridge between an initial loading/unloading position and a loaded position in which the cartridge within the shuttle engages the digital tape drive.